Probabilistic Seismic Hazard Analysis for Tehran and suburbs by using of First Order Second Moment Algorithm

One of the most damaging natural disasters is earthquake which random process of its motions has made predicting and preventing of its occurrence impossible; but it is possible to reduce the probable damages caused by earthquakes through probabilistic seismic hazard studies. The experiments of many countries that are at high risk of earthquakes, has shown that damages can be reduced when seismic hazard analysis is achieved in structural design process. Seismic hazard analysis requires earthquake data and obviously more accurate data can lead to results with more precision. The magnitude, location and focal depth of earthquake are the most basic data that needs to be updated carefully. These parameters have a major role in the estimation of probabilistic seismic hazard analysis in different regions. The current research includes a history of more than 300 earthquakes in the past 117 years, which has been analyzed for Tehran and its suburbs with the aim of conducting a new FOSM (First Order Second Moment) algorithm. Based on given design seismic levels and the Iranian Standard No.2800, the present study has PGA in two levels. The first level which is, Design Basis Earthquake(DBE) defines the peak horizontal accelerations with 10%probability of exceedance in 50years that is expected to occur once in approximately 475 years. The second is Maximum Considered Earthquake(MCE) that defines the peak horizontal accelerations with 2%probability of exceedance in50years which is expected to occur once in approximately 2,475years. According to the FOSM algorithm the estimated PGA for both level are0.30061g and0.55666g, respectively.